Aotus New World monkeys: model for studying malaria-induced anemia.

Falciparum malaria is a major cause of disease and death in African children and pregnant women, primarily due to severe anemia. We studied anemia in vaccinated Aotus monkeys during a second infection where the animals were considered to be semi-immune. Most animals had extremely low or undetectable levels of parasitemia; in some, anemia did not develop and reticulocytemia remained unchanged; in others, moderate to severe anemia developed with inappropriately low reticulocytemia indicating bone marrow dysfunction. Bone marrow rapidly responded after parasite clearance. The rapid drop in hematocrit despite extremely low to undetectable parasitemia indicated massive removal of uninfected red blood cells from the circulation that, in the presence of bone marrow dysfunction, led to severe anemia-the problem that occurs in African children. We demonstrate that Aotus monkeys are a nonhuman primate model to gain insight into the pathogenesis of severe anemia in African children.